Air blast circuit breakers with breaking gaps in compressed air containers carried by insulator pillars



Feb.-2l, 1961 H. FORWALD 2,972,666

AIR BLAST CIRCUIT BREAKERS WITH BREAKING GAPS IN COMPRESSED AIR CONTAINERS CARRIED BY INSULATOR PILLARS Filed June 19, 1958 2 Sheets-Sheet 1 Fig. 1

INVENTOR. fllswo/v F a A 2,972,666 WITH BREAKING GAPS IN COMPRESSED AIR CONTAINERS CARRIED Feb. 21, 1961 H. FORWALD AIR BLAST CIRCUIT BREAKERS BY INSULATOR PILLARS 2 Sheets-Sheet 2 Filed June 19, 1958 AIR BLAST CIRCUIT BREAKERS WITH BREAKING GAPS IN COMPRESSED AIR CONTAINERS CAR- RIED BY INSULATOR PILLARS Haakon Forwald, Ludvika, Sweden, assignor to Allmanna Svenska Elektriska Aktiebolaget, Vasteras, Sweden, a corporation of Sweden The present invention concerns a compressed air circuit breaker with breaking gaps arranged in compressed air containers permanently filled with air under pressure and carried by insulating pillars. Each container contains generally one breaking gap. The stationary contact of said breaking gap is carried by a leading-through insulator inserted in one wall of the container, whereas its movable contact, being a nozzle contact, is arranged together with an operating mechanism in a mechanism housing inserted in the wall of the container opposite to the wall carrying the leading-through insulator. An air blast valve located in the close vicinity of the breaking gap contains a sealing member rigidly attached to the movable contact.

' The circuit breaker according to the invention is mainly characterized in that an outlet valve coupled in series with the blast valve is arranged to block after an interruption an outlet opening from the air blast channel and to hold this outlet opening blocked until the breaking gap has been closed after operation of the circuit breaker.

The valve member of the outlet valve consists suitably of a movable operating cylinder in which there is a piston which is stationary in relation to a valve seat. In one form of the invention there will thus be a space limited by the operating cylinder and the piston of the cylinder, which space is by two channels in communication with an operating cylinder for an operating piston joined with the movable contact, which channels terminate in the latter of said cylinders in such a way that the outlet valve is controlled by the operating piston of the movable contact. One of these channels should, when the breaking gap is closed, terminate in the space on that side of the operating piston which is in permanent communication with the open air, whereas the'other channel should, when the breaking gapis opened, terminate in the space onthat side of the piston which then is filled with operating air under pressure. The operating cylinder of the outlet valve is suitably attached to the operating cylinder of the movable contact over a non-return valve, which prevents the blocking valve from being opened before the breaking gap has been closed. In another design of the valve the said space formed by the operating cylinder and the piston is over a throttle valve in communication with the operating air pipe line for the movable contact. A cooling grid is suitably arranged in the outlet channel for the extinguishing air between the movable contact and the outlet valve. The outlet area of the valve can then .be made smaller than the operating area of the cooling grid, because the volume of the gases decreases when they are cooled by the cooling grid.

The invention makes it possible in circuit breakers with an air blast valve in close vicinity of the breaking gap, having the movable valve member carried by the movable contact of the breaking gap, to obtain an insulating distance which is under pressurewhen the breaker is open, in spite of the fact that atmospheric pressure prevails in the outlet channel for the extinguishing air, when the United States atent' O circuit breaker is closed. This is a very important advantage, because the breaking mechanism for circuit breakers of said kind with a valve member carried by the movable contact may be made very simple and reliable in operation. Another advantage is that the outlet valve can be entirely controlled without separate operating air pipe lines and can be made in a very simple manner entirely dependent upon the position of the movable contact, so that it is guaranteed that the outlet valve closes the outlet opening only when the breaking gap is entirely open.

In the drawings:

Fig. l is a cross-section through one form of the invention; and

Fig. 2 is a cross-section through a different form.

In Fig. 1, 1 designates a container permanently filled with compressed air and carried by an insulator pillar not shown on the drawing, in which container a breaking gap is enclosed. The stationary contact 2 of the breaking gap is carried by a leading-through insulator 3 inserted in one wall of the container 1, and is provided with an annular flange 4, in which a sealing ring 5 is inserted. In the wall of the container opposite the leading-through insulator a mechanism housing 6 is inserted, in which a movable nozzle formed contact piston 7 and an operating piston 9, joined with it by the operating rod 8, and

a blocking valve 10 are arranged. The movable contact piston carries at its upper part a valve disc 11 with a central opening, which valve disc, in the closed position of the breaking gap, is pressed against the sealing ring 5, and contact blocks 12 being radially inwardly actuated by springs 13, which blocks form a nozzle contact. 14 designates spring loaded contacts for transmitting current from the mechanism housing 6 to the movable contact 7. A spring 15 which rests on the bottom 16 in the operating cylinder 17 and against the operating piston 9, acts on the movable contact 7 in closing direction. The space 20 above the operating piston 9 is via an operating air line 21 in communication with an operating valve, not shown on the drawing. 22 designates a cooling grid arranged in an air blast channel 23 between the movable contact piston 7 and the blocking valve 10. The mechanism housing 6 is provided with a cylindrical stem 24 which projects from the wall of the operating cylinder 17, and is concentric with the outlet opening 25 and the valve seat 26 of the blocking valve. 27 is a disc attached to the outermost end of the cylindrical stem 24. The valve member 28 of the blocking valve 10 is actuated in the closing direction by a spring 29, which has for its single purpose to hold the valve member 28 in contact with the valve seat 26, when the circuit breaker is in its closed position. The pressure in the channel 23 will then be equal to or slightly exceed the atmospheric pressure. The space 30 in the valve member 28 is through openings 31 and 32 in communication with channels 33 and 34, which terminate on diiferent levels in the operating cylinder 17. In the channel 34 there is a non-return valve 35. There is nothing to prevent the valve member 28 of the blocking valve being actuated by a spring force acting on the valve member 28 in opening direction, so that the blocking valve will be entirely open when the breaker is closed.

The circuit breaker with a breaking chamber according to the design illustrated in Fig. 1 acts in the fol owing way. The breaking gap is opened when compressed air is delivered to the space 20 above the operating piston 9 through the operating air line 21. When the operating piston 9 and the movable contact joined with it are moved downwards, the blast valve, formed by the valve disc 11 and the flange 4, is opened and extinguishing air streams from the container through the nozzle in the movable contact piston 7 into the outlet channel 23, where normal atmospheric pressure prevails. When the pressure in the outlet opening rises, the blocking valve is immediately opened as the air fiow moves the valve member 28 aside. When the operating piston has reached its lower position, its upper part has passed the end of the channel 34 in the cylinder 17, so that compressed air streams from the space 20 through the channel 34, the non-return valve 35 and opening 32 to the space 30. Under the influence of the pressure in this space the valve member 28 is moved to the right and closes the outlet opening 25, so that the extinguishing air flow ceases. The breaking gap is closed when the space 20 above the operating piston 9 is evacuated through the operating air line 21. The spring will then move the movable contact to its upper position so that the blast valve is also closed. When the operating piston 9 has reached its upper position, the lower part of the piston will be above the end of the channel 33 in the cylinder 17. The space 30 will then be in communication with the open air so that air can escape from this space and the valve member 28 will thus be actuated only in one direction against its valve seat by the spring 29. The air in the outlet channel 23 will then flow out through the blocking valve.

In Fig. 2, 51 designates a container permanently filled with compressed air and enclosing a breaking gap, said container being carried by the insulating pillar, not shown on the figure. The stationary contact 52 of the breaking gap is carried by a leading-through insulator 53 inserted in one wall of the container, said insulator being provided with an annular flange 54, in which there is a tightening ring 55. In the part of the container wall opposite the leading-through insulator a mechanism housing 56 is inserted in which a nozzle formed contact piston 57 is movably arranged. This contact piston is provided with an inner cylindrical part 58 carrying contact blocks 60 actuated by springs 59, which blocks form a nozzle contact, and with an outer cylindrical part 61 concentric with this contact, these two parts projecting from the annular plate 62 forming the movable valve disc in the air blast valve. 63 is a spring actuating the movable nozzle contact in closing direction. In the outlet channel in the movable contact piston there is an arcing contact 64 and a cooling grid 65. The mechanism housing is provided with a cylindrical part 66, which projects in between the cylindrical parts 58 and 61 of the movable contact piston, so that a space 67 is formed that is separated from the part of the container which is filled with compressed air. This space communicates with a valve housing 68, which by means of the valve member 70 operated by the membrane 69, may be alternatively in communication with the compressed air container through the pipe line 71 or with the open air through the outlet opening 72. Attached to the valve housing 56 is a blocking valve 73 with a valve seat arranged at the outlet opening 74 on the outer part of the extinguishing air channel 75. The blocking valve contains a bottom plate 77 attached to the mechanism housing 56 by means of bolts 76, which carries a stationary piston 78. 79 is a movable valve member provided with a bottom 80. Between the bottom 80 and the piston 78 there is a spring 81 actuating the valve member in opening direction. The space 82 above the piston 78 is via the channel 83, a throttling device '84 and pipe line 85 in communication with the operating air line 86 for operating the valve member 70 joined with the membrane 69.

The circuit breaker with the breaking chamber shown in Fig. 2 acts in the following way. When'the circuit breaker shall be opened, compressed air'is delivered to the operating pipe line 86, so that the membrane 69 lifts the valve member 70 to a tightening contact with the end of the pipe line 71 in the valve housing 68. Thereby the compressed air in the space 67 will flow out and thus the movable contact piston 57 will be moved downwards due to the influence of the air pressure in the container. Then the breaking gap as well as the blast valve will be opened. Simultaneously air flows through line 85, throttle valve 84 and channel 83 to the space 82. When the pressure in the space rises, the valve member 79 is lifted and closes, after a time lag determined by the throttling device 84, the outlet opening 74, so that the flow of extinguishing air is interrupted. The time for the closing of the blocking valve is so chosen that an interrupting are certainly will be extinguished before the closing.

The breaking gap is closed by evacuating the operating air line 86 so that the valve member 70 will go back to the position shown in the figure. Air flows out from the compressed air container into the space 67. The movable contact is lifted under the influence of the spring 63 and the pressure in the space 67, so that the breaking gap and blast valve are closed. Simultaneously air flows out from the space 82 through the throttling device 84. The blocking valve is then opened after a certain time by the spring 81.

I claim as my invention:

1. Air blast circuit breaker with containers permanently filled with compressed air carried by insulating pillars and enclosing a breaking gap the stationary contact of which is carried by a leading-through insulator inserted in one wall of the container and its movable contact being a nozzle contact, which together with operating members is arranged in a mechanism housing inserted in the wall of the air container opposite the leading-through insulator, comprising an air blast valve consisting of a valve member joined with the said nozzle formed contact, which valve member, when the breaking gap is closed, rests tightly against the stationary contact, and an outlet valve which is arranged to block, after an interruption, an outlet opening in a gas escape channel leading from said blast valve and to hold this outlet opening blocked until the breaking gap has been closed after closing the circuit breaker.

2. Circuit breaker according to claim 1, characterized in that an operating cylinder for the air blast valve is, via two channels, in communication with an operating cylinder for an operating piston joined with the movable contact, said channels terminating in the operating cylinder in such a way that the outlet valve is controlled by the operating piston.

3. Circuit breaker according to claim 2, characterized in that the operating cylinder of the outlet valve is connected to the operating cylinder for the movable contact over a back valve which prevents the outlet valve from being opened before the breaking gap is closed.

4. Circuit breaker according to claim 1, characterized in that the operating cylinder of the outlet valve is connected to the operating air line for the movable contact over a throttle valve which determines the moment of closing the outlet valve.

References Cited in the file of this patent UNITED STATES PATENTS 2,665,351 Forwald Jan. 5, 1954 2,724,751 Forwald Nov. 2, 1955 2,766,348 Forwald Oct. 9, 1956 FOREIGN PATENTS 322,589 Italy Nov. 6, 1934 660,394 Germany May 21, 1938 93,212 Sweden Nov. 5, 1938 512,400 Great Britain Sept. 1, 1939 

